Tanzawaic Acid Derivatives from the Marine-Derived as Inhibitors of RANKL-Induced Osteoclastogenesis.

Seven new tanzawaic acid derivatives, steckwaic acids E-K (-), and one new benzene derivate (), together with seven known tanzawaic acid analogues (-) were isolated from the marine algicolous fungus SCSIO 41040. The structures and absolute configurations of these new compounds (-) were determined by spectroscopic analyses, X-ray diffraction, and comparison of ECD spectra to calculations. Compounds , , and inhibited lipopolysaccharide (LPS)-induced nuclear factor kappa-B (NF-κB) with IC values of 10.4, 18.6, and 15.2 μM, respectively. Compound could suppress the receptor activator of NF-κB ligand (RANKL)-induced osteoclast differentiation in bone marrow macrophage cells (BMMCs). To the best of our knowledge, this is the first report of osteoclastogenesis inhibitory activity for tanzawaic acid derivatives.